Indispensable Thing of Wireless World: MODULATION ~ All about Wireless Technologies

Modulation, we are facing this thing every single day if we are listening radio ,television or using mobile phone.
I will try to explain this to you in simply way as it may seem simple, the transmission and reception of information is quite complex, considering the many possibilities and scenarios where this may occur.
We will not go deep into advanced mathematical operations like Fourier Transform,Impulse Functions or Shannon theorem etc. Our goal is endearing modulation to our valuable followers.

So let's start it;

If you are not talking with your friend in close distance, so you need a device to be able to hear his/her voice.
In history, we had used smoke or pigeon etc instead of voice. Now we can use more smart devices like mobile phone. Let's consider our voice is data signal and we want to carry it to very long distances so we have to use high frequency carrier as low-frequencies can not carry this data to long distances.
Why we have to use carrier signal instead of our voice? reason will send us to the very important result. Which is modulation. Basically from our school years, electro-magnetic waves theory will answer this question.
Voice frequency is ~3 kHz. It means that we need height of antenna equal to 100 km! This is practically impossible! However we can reduce its height by l/2, l/4, l/8 or up to l/16. But even if we reduce it to l/16, it becomes 6.2km, which is still impossible!
To be able to use proper antennas we need modulation and we need to do some processes in like following figure.

So we need to carry our signal by modulating it. but after receiving we need to do reverse process which is called demodulation.

More concepts ...

Modulation : changing the characteristics of the signal being transmitted.
Demodulation , the reverse process of modulation.

Before our voice is to be transmitted, it must be converted. For this reason, there are digital devices that convert analog voice through a process of sampling and quantization.
In GSM, we are generally using PCM (Pulse Code Modulation) shown in above. Between the maximum amplitude and minimum signal levels are set 16 (0 to 15), and these are encoded as binary numbers (0000, 0001, ..., 1111).

We can classify the modulation types as ;

Frequency
Amplitude
Phase

We will try to explain modulation types in next blog especially in GSM perspective.Thanks and please do not hesitate to share your ideas, questions and comments anytime.